At present, it has been clarified that periodontitis, one of diseases of periodontal tissue is mainly caused by bacteria forming colonies on tooth root surface. As a treatment thereof, main effort is laid on to maintain the periodontal tissue under plaque-free condition by mechanical removing the bacterial plaque adhered to the tooth surface mainly by scaling.
A periodontal surgery applied to serious periodontitis is also performed on purpose to improve environment so as to make oral cleaning more effective, by removing causative factors such as tartar and plaque adhered to a root surface in a periodontal pocket, and pathologic tissue in the same manner as in the above-mentioned therapy. Furthermore, recently chemotherapies with antibiotics are also tried in addition to these therapies.
However, although these therapies remove the pathologic lesion and inhibit progress of the periodontitis, they do not positively repair or regenerate destroyed periodontal tissue. A profile of postoperative curing depends on self healing ability.
Curing forms are classified into regeneration curing (new attachment curing), and reattachment curing. The regeneration curing contains a curing form of cementum morphogenesis wherein collagen fibers are embedded in the postoperatively exposed root surface (new attachment curing) develops with the regeneration of alveolar bone.
On the other hand, the reattachment is a curing containing a long epithelial attachment recognized on the root surface or the accumulation of collagen fibers onto the root surface where a functional recovery can not be desired.
Heretofore, a large number of basic and clinical studies have shown that many forms of postoperative curing forms are reattachment curing. According to histopathological studies, most reattachments are caused by epithelial attachment which formed by the down growth of epithelial cells apically directed from gingival margin, and new attachment is hard to develop.
Particularly, progressed periodontitis is accompanied by complex pocket morphogenesis and various types of osteoclasia, and the bone regeneration is impossible, where the large amount of bone resorption is observed. Melcher (Melcher, A. H.: J. Periodontol., 47, pp 256-260, 1976) has also reported that the proliferation of cells derived from periodontal ligament is necessary to the recovery of the periodontal tissue with the new attachment to the exposed root surface, and that a long junctional epithelium formation, root resorption and ankylosis develop when the cells reaching the root surface are epithelial cells, cells derived from gingiva or cells derived from bone.
From these information, the following subjects have been investigated basically or clinically on purpose to achieve the regeneration curing;
(1) a treatment of the root surface with citratic acid, PA1 (2) a local administration of fibronectin, PA1 (3) "a guided tissue regeneration method (GTR method)" which inhibits the down growth of epithelial cells using a highly bio-compatible filter and guides the cells derived the periodontal ligament to the root surface, PA1 (4) an implantation into a bone-defected site using various implant materials for the resorption of the alveolar bone, and PA1 (5) a local administration of Bone Morphogenetic Protein, and the like.
However, they have various problems such as a irritation upon the cells in (1), the stability and antigenicity of fibronectin which is a macromolecule in (2), the necessity of the reoperation for removing of the above-mentioned filter in (3), also complexity of harvest, storage, sterilizing and the ability to be resorbed of the implant material in (4), and easy occurrence of ankylosis in (5). Therefore, the development of an agent for accelerating periodontal tissue regeneration which has safety, easiness of formulation and efficiency is desired.
In the present invention, the purpose is to provide the above-mentioned therapeutic agent for diseases of periodontal tissue which has excellent safety and efficiency, a process for treating diseases of periodontal tissue, an accelerator for fixing osseo-integration between a bone and an implant, and a therapeutic agent for dentin regeneration.